Machine gun with adjustable packing



Dec. 20, 1938. F. T. MOORE I MACHINE GUN WITH ADJUSTABLE PACKING Filed Feb. 18, 1955 fnvsntaz" Frederzg I M00215 f. f

Patented Dec. 20, 1938 UNETED STATES PATEE NT OFF'I CE MACHINE GUN WITH ADJUSTABLE PACKING Connecticut Application February 18, I935, SerialNo. 7,129

13 Claims.

In a machine gun of the liquid cooled reciprocating barrel type, it is necessary to provide a packing near the rear of the barrel to prevent leakage of cooling liquid or coolant water into the interior of the casing. It is desirable that the packing be adjustable to compensate for wear, and it is also desirable that the packin be as far to the rear as possible so as to permit the coolant to extend far enough to the rear to at least surround the hot zone adjacent the front end of the cartridge chamber.

Difliculty has heretofore been encountered in meeting both of these requirements, and in earlier constructions the desired packing adjustment has been sacrificed in order to get the packing far enough to the rear, or the desired rear position of the packing has been sacrificed in order to make provision for adjustment. An important object of the present invention is to provide a construction wherein the packing is adjustable and is also in the desired rear position.

A further object of the invention is to provide a gun having a packing adjusting means which is so constructed as to be readily accessible from the exterior of the gun, it being thus possible to adjust the packing at any time with a minimum of effort and delay and without disassembling the gun or any essential parts thereof.

Other objects of the invention will be apparent from the following specification and claims.

In the accompanying drawing 1- have shown the embodiment of the invention which I now deem preferable, but it will be understood that the drawing is intended for illustrative purposes only and is not to be construed as defining or limiting the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

Of the drawing:

Fig. 1 is a fragmentary longitudinal vertical sectional view showing the central portion of a machine gun, the barrel and other parts being shown in elevation, or partly in elevation.

Fig. 2 is a transverse vertical sectional view taken along the line 22 of Fig. 1.

Fig. 3 is a view somewhat similar. to Fig; 1,: but showing the cover and attached parts inraised position and showing the barrel and associated parts in retracted position.

The present invention is adapted to be used. in a gun of the type disclosed in Patent No. 1,628,226 issued May 10, 1927 to John M. Browning. Reference may be had to the said patent for details of mechanism not herein fully disclosed.

The machine gun casing, as shown in part in Fig. 1, includes a trunnion block I and side plates 2, 2 secured to thetrunnion block by riveting or otherwise. The trunnion block is provided with a longitudinal hole through which the barrel 4 extends. The barreld is longitudinally movable for purposes of assembly-and disassembly and it is preferably reciprocable during firing as set forth in detail in the before-mentioned patent. The front portion 3 of the hole is considerably larger than the barrel, but the rear portion 3 of the hole constitutes -a bearing aperture which fits or approximately fits the rear portion 4 of the-barrel. A reciprocable'barrel extension 5 is provided within-the casing, and the said barrel and barrel extension 5 are provided with interengaging retaining means normally serving to hold-them in'fixed relation but adapted upon barrel rotation torelease the said barrel and permit separation by relative longitudinal movement. Preferably and as shown the'barrel extension" has an internally threaded hole and the rear portion of the barrel is externally threaded toenteran'dfit the threaded hole. The'barrel preferably also has bevelled notches 1,-1 adapted to-be engaged by aspring detent 8 on the extension for holding the barrel against rotation under normal conditions.

*It will be-apparent that the barrel may be connected-with or disconnected'fromthe' barrel extension by rotation with respect thereto, the barrel being automatically held in adjusted position by means ofthe engagement of the spring detent 8 with one or another of the notches 1,1. As shown i-n -Fig. '2 a recess may be provided if necessary in'the casing-adjacent the latch -8so as to leave the latch free to move into or out of the notches, even whenthe barrel extension and barrel are bothin-place in the casing. The-barr'el i i and thebarrel extension 5 move rearward -as the result =of recoil, being shown in their retracted positions in Fig.3. The barrel extension 5 carries .ap-breech bolt/9 which is capable of longitudinal movementadditional to that of the barrel extension. Carried by the breech bolt is a longitudinally movable firing pin H).

The. longitudinal'top wall of the casing is provided With an opening adjacent the rear end of the bearing aperture, this opening being normally closed by a cover- 12 which is pivoted to the trunnionblock at I I. This cover carries certain parts of the'g-un mechanism, including a portion of the cartridgefeed mechanism particularly the reciproc'ating feed slide I3. Another portion of the cartridge 'feedmechanism including the extractor t3 is carried-within the casing independently of the cover. The cover can be raised to the position shown in Fig. 3, and when so raised it may be automatically held by means of a spring pressed detent M. The cover I 2 when raised or open serves to permit access to both of the said portions of the feed mechanism. The details of the gun mechanism do not of themselves constitute any part of the present invention, and further description of them can be omitted. These details are, or may be, similar to what is shown in the aforesaid patent.

Carried by a forward projecting portion [5 of the trunnion block is an adapter l6 which is held in place by threads and prevented from rotation by means of a spring pressed detent l 'l. Carried by the adapter I6 is a coolant jacket l8 which extends forward throughout the greater portion of the length of the barrel. This-coolant jacket serves to hold a body of coolant which surrounds the barrel to prevent it from overheating when the gun is in use. As will be observed in Figs. 1 and 3, the coolant extends rearward around the barrel into the larger front portion 3 of the hole in the trunnion block. The coolant extends rearward so as to surround the zone adjacent the front end of the cartridge chamber, which zone tends to become greatly heated if firing is continued throughout an extended period.

As already stated, the rear portion 4 of the barrel approximately fits the bearing aperture 3 in the trunnion block, but in order to prevent any leakage of coolant rearward into the interior of the casing an annular packing I9 is provided, this packing being carried by the barrel and engaging the inner surface of the bearing aperture 3 In order that the packing I9 may be adjusted so as to make it initially tight and so as to compensate for wear, there is provided an adjusting means which is adjacent the packing and movable with the barrel. This means is preferably a ring 20 which is in threaded engagement with the barrel and which can be rotated on its threads to compress and expand the packing to the extent desired. The ring 20 is provided with holes 2! to facilitate engagement of the ring and rotation thereof by means of a spanner wrench. The annular walls on the barrel and on the ring adjacent the packing are preferably inclined so as to more effectively hold the packing in place.

Preferably the barrel at the rear of the packing 19 and the ring 20 is of approximately the same diameter as at the front of the packing, and the said packing and the said ring are therefore positioned in an annular groove in the barrel. The groove is preferably so located that it is entirely within the bearing aperture 3 when the barrel is in its forward normal position as shown in Fig. 1. The ring 20 is preferably integral and continuous, and therefore in order to permit assembly the portion of the barrel at the rear of the ring, preferably consists of a second ring 22, which is permanently secured to the main body of the barrel, as for instance by means of screws 23. The screws 23 are preferably headless, the outer ends of the screws being ground 01f flush with the periphery of the ring.

As already stated, the barrel and the barrel extension are'reciprocable. They move rearward from the normal position shown in Fig. 1 upon the firing of each cartridge and are automatically returned following the automatic extracting of the empty cartridge shell and the automaticfeeding of a new cartridge into position in the chamber. During this automatic movement the 2,14.o,sos

packing 19 remains within the bearing aperture 3 in the trunnion block, thus preventing leakage for all positions of the barrel. In order to economize space and to locate the packing l9 as far to the rear as possible, the ring 20 is made relatively narrow and is so positioned that it is normally substantially entirely concealed within the hole 3', as shown in Fig. 1. Adjustment of the pack- I ing by rotating the ring Zil may be effected with the barrel entirely removed from the gun or with the barrel and barrel extension withdrawn rearward and removed from the gun in assembled relationship as set forth in the said Browning patent. Preferably, however, the packing adjusting means is so arranged as to be accessible for adjustment from the exterior of the gun with the barrel extension in the casing and with the barrel in normal engagement with the extension. The opening which is normally closed by the cover 12 constitutes an opening in a longitudinal wall of the casing, this opening being adjacent the rear of the bearing aperture 3. When the barrel is moved rearward from its normal position to the retracted position shown in Fig. 3, a sufiicient portion of the ring 28 isexposed to permit access to be had to the holes 2|, 2!. Such access is had through the same opening in the top wall of the casing which is necessarily provided as already stated to afford access to the feed mechanism. A suitable tool such as a spanner wrench may be inserted through the said opening and engaged with the holes 2!, 2| in the ring 20. It will be understood that in adjusting the ring the cover I2 is raised to the position showrr in Fig. 3.

In the embodiment of the invention as shown and described, the latch 8 and the notches l, I serve merely to resist free rotation of the barrel but do not positively prevent such rotation. It is therefore desirable to provide means additional to the latch 8 and the notches 'l for positively preventing rotation of the barrel during adjustment of the rotatable ring 20. For this purpose the rear portion of the barrel, more specifically the ring 22 thereon, is provided with means such as holes 6, 6 adapted to be engaged by a suitable tool such as a spanner wrench. It will be apparent that with the cover l2 raised, as shown in Fig. 3, two separate tools may be inserted through the cover opening, one tool engaging the holes 6 in the rear portion of the barrel to positively prevent barrel rotation, and the other tool engaging the holes 2! in the ring 29 to cause rotation of the ring and thus eifect adjustment of the packing.

What I claim is:

1. Ina machine gun, the combination of a casing having a longitudinal barrel receiving bearing aperture at the front, a barrel extending through the said aperture and longitudinally movable therein, means within the casing to which the barrelis connected. at its rear, a coolant jacket carried by the casing at the front thereof and surrounding the barrel, an annular packing carried by the barrel and engaging the interior surface of the bearing aperture in the casing for preventing leakage of coolant from the jacket into the interior of the casing, and a rotatable ring adjacent the packing and having threaded engagement with the barrel, the said ring being normally at least partly within the bearing aperture and being accessible at the rear of the said aperture to permit adjustment when the barrel is in its retracted position.

52. In amachine gun, the combination of a casing having a longitudinal barrel receiving hearing aperture at the front, a longitudinally reciprocable barrel extending through the said bearing aperture, that portion of the barrel which is normally within the aperture having an annular groove therein, means within the casing to which the barrel is detachably connected at its rear, a coolant jacket carried by the casing at the front thereof and surrounding the barrel, an annular packing carried by the barrel within the said groove for preventing leakage of coolant from the jacket into the interior of the casing, and a rotatable ring within the said groove adjacent the packing and having threaded engagement with the barrel, the said ring being normally at least partly within the bearing aperture and being accessible at the rear of the said aperture to permit adjustment when the barrel is in its retracted position.

3. In a machine gun, the combination of a main casing having a longitudinal barrel receiving bearing aperture at the front, a longitudinally reciprocable barrel fitting the aperture and having its rear portion in the casing, a coolant jacket carried by the casing at the front thereof and surrounding the barrel, an annular packing carried by the barrel and engaging the interior surface of the bearing aperture and serving to prevent leakage of coolant into the interior of the casing, a longitudinally reciprocable barrel xtension in the casing, interengaging retaining means on the barrel and extension normally serving to hold them in fixed relation but adapted upon barrel rotation to permit separation by relative longitudinal movement, means on the extension additional to the said retaining means and engaging the barrel to resist rotation thereof, and packing adjusting means carried by the barrel in front of the rotation resisting means and normally at least partly within the bearing opening in the casing.

4. In a machine gun, the combination of a main casing having a longitudinal barrel receiving bearing aperture at the front, a longitudinally reciprocable barrel fitting the aperture and having its rear portion in the casing, that portion of the said barrel which is normally within the bearing aperture having an annular groove therein, a longitudinally reciprocable barrel extension in the casing, the said barrel and extension having interengaging retaining means normally serving to hold them in fixed relation but adapted upon barrel rotation to permit separation by relative longitudinal movement, means on the extension additional to the said retaining means and engaging the barrel behind the said groove therein to resist barrel rotation, a coolant jacket carried by the casing at the front thereof and surrounding the barrel, an annular packing carried by the barrel within the said annular groove therein and serving to prevent leakage of coolant into the interior of the casing, and a rotatable ring within the saidannular groove adjacent the packing and having threaded engagement with the barrel whereby it may be used to adjust the packing.

5. In a machine gun, the combination of a casing having a longitudinal barrel receiving bearing aperture at the front and having in a longitudinal wall thereof an opening adjacent the rear end of the said bearing aperture, a barrel extending through the said bearing aperture and longitudinally movable therein, means within the casing to which the barrel is connected at its rear, a coolant jacket carried by the casing at the front thereof and surrounding the barrel, an annular packing carried by the barrel and engaging the interior surface of the bearing aperture for preventing leakage of coolant from the jacket into the interior of the casing, and packing adjusting means carried at least in part on thebarrel adjacent the packing and operable from the exterior of the casing through the said opening therein.

"6. In a machine gun of the type described having a main casing with a longitudinal barrel receiving bearing aperture at the front and with an opening in the top wall thereof adjacent the rear end of the said bearing aperture which casing opening primarily serves to afford access to a portion of the cartridge feed mechanism within the casing, an openable cover normally closing the casing opening and carrying another portion of the cartridge feed mechanism which cover serves when open to permit access to both of the said portions of the feed mechanism, a barrel extending through the said bearing aperture and longitudinally movable therein, means within the casing to which the barrel is connected at its rear, and a coolant jacket carried by the casing at the front thereof and surrounding the barrel, the combination with the aforesaid parts of an annular packing carried by the barrel and engaging the interior surface of the bearing aperture for preventing leakage of coolant from the jacket into the interior of the casing, and packing adjusting means carried at least in part on the barrel adjacent the packing and so positioned with respect to the barrel that it is accessible for operation through the aforesaid casing opening which is primarily provided for affording access to the feed mechanism.

7. In a machine gun, the combination of a casing having a longitudinal barrel receiving bearing aperture at the front and having in a longitudinal wall thereof an opening adjacent the rear end of the said bearing aperture, a barrel extending through the said bearing aperture and longitudinally reciprocable therein, reciprocable means within the casing to which the barrel is connected at its rear, a coolant jacket carried by the casing at the front thereof and surrounding the barrel, an annular packing carried by the barrel and engaging the interior surface of the bearing aperture for preventing leakage of coolant from the packet into the interior of the casing, and packing adjusting means carried by the barrel adjacent the packing and at the rear thereof, the said adjusting means being so positioned with respect to the barrel that it is entirely within the bearing aperture when the barrel is in its forward position and is at least partly outside of the bearing aperture and being accessible and operable from the exterior of the casing through the said opening therein when the barrel is in its rearward position. v

8. In a machine gun, the combination of a main casing having a longitudinal barrel receiving bearing aperture at the front and having in a longitudinal wall thereof an opening adjacent the rear end of the said bearing aperture, a 1ongitudinally reciprocable barrel fitting the bearing aperture and having its rear portion in the casing, a longitudinally reciprocable barrel extension in the casing, interengaging retaining means on the barrel and extension normally serving to hold them in fixed relation but adapted upon barrel rotation to release the said barrel and permit separation by relative longitudinal movement, a coolant jacket carried by the casing at the front thereof and surrounding the barrel, an annular packing carried by the barrel and engaging the interior surface of the bearing aperture and serving to prevent leakage of coolant into the interior of the casing, a rotatable ring adjacent the packing at the rear thereof and having threaded engagement with the barrel whereby it may be used to adjust the packing, the said ring being so positioned with respect to the barrel that it is accessible and operable from the exterior of the casing through the said opening therein, and means on the barrel near the rear thereof and adapted to be engaged by a tool inserted through the opening in the casing to positively prevent rotation of the barrel during rotation of the adjusting ring.

9. In a machine gun of the type described having a main casing with a longitudinal barrel receiving bearing aperture at the front and with an opening in the top wall thereof adjacent the rear end of the said bearing aperture which casing opening primarily serves to afford access to a portion of the cartridge feed mechanism within the casing, an openable cover normally closing the casing opening, a longitudinally reciprocable barrel fitting the bearing aperture and having its rear portion in the casing, a longitudinally reciprocable barrel extension in the casing, interengaging retaining means on the barrel and extension normally serving to hold them in fixed relation but adapted upon barrel rotation to release the said barrel and permit separation by relative longitudinal movement, and a coolant jacket carried by the casing at the front thereof and surrounding the barrel, the combination with the aforesaid parts of an annular packing carried by the barrel and engaging the interior surface of the bearing aperture and serving to prevent leakage of coolant into the interior of the casing, a rotatable ring adjacent the packing at the rear thereof and having threaded engagement with the barrel whereby it may be used to adjust the packing, the said ring being so positioned with respect to the barrel that it is accessible and operable from the exterior of the casing through the aforesaid casing opening which is primarily provided for affording access to the feed mechanism, and means on the barrel near the rear thereof and adapted to be engaged by a toolinserted through the aforesaid casing opening to positively prevent rotation of the barrel during rotation of the adjusting ring.

10. In a machine gun of the type described having a main casing with a longitudinal barrel receiving bearing aperture at the front and-with an opening in the top wall thereof adjacent the rear end of the said bearing aperture which cas ing opening primarily serves to afford access to a portion of the cartridge feed mechanism within the casing, an openable cover normally closing the casing opening, a longitudinallyreciprocable barrel fitting the bearing aperture and having its rear portion in the casing, the said barrel having an annular series of notches therein near its rear end, a longitudinally reciprocable barrel extension in the casing, interengaging retaining means on the barrel and extension normally serving to hold them in fixed relation but adapted upon barrel rotation to release the said barrel and permit separation by relative longitudinal movement, means on the barrel extension for engaging the barrel at the said notches therein to resist rotation without positively preventing it, and a coolant jacket carried by the casing at the front thereof and surrounding the barrel, the combination with the aforesaid parts of an annular packing carried by the barrel and engaging the interior surface of the bearing aperture and serving to prevent leakage of coolant into the interior of the casing, a rotatable ring adjacent the packing at the rear thereof and having threaded engagement with the barrel whereby it may be used to adjust the packing, the said ring being so positioned with respect to the barrel that it is accessible and operable from the exterior of the casing through the aforesaid casing opening which is primarily provided for affording access to the feed mechanism, and means on the barrel near the rear thereof and adapted to be engaged by a tool inserted through the aforesaid casing opening to positively prevent rotation of the barrel during rotation of the adjusting ring.

11. For a machine gun, the combination of a reciprocable barrel provided with means at its rear end adapted by rotative barrel movement to effect engagement with or disengagement from a machine gun part such as a barrel extension, the said barrel having adjacent the last said means an annular series of bevelled notches and also having means thereon additional to the said notches and adapted to be engaged by a tool to prevent rotation, an annular packing carried by the barrel in front of the said notches and the rotation preventing means, and a rotatable adjusting ring for the packing carried by the barrel and having threaded engagement therewith, the said ring having its maximum diameter at least as small as the diameter of the barrel immediately adjacent the packing.

12. For a machine gun, the combination of a reciprocable barrel provided with means at its rear end adapted by rotative barrel movement to effect engagement with or disengagement from a machine gun part such as a barrel extension, the said barrel having means thereon adjacent the last said means and adapted to be engaged by a tool to prevent rotation and the said barrel having an annular groove therein in front of the said rotation preventing means, an annular packing carried by the barrel within the said groove, and a rotatable adjusting ring for the packing positioned within the said groove and having threaded engagement with the barrel, the said ring having its maximum diameter at least as small as the diameter of the barrel immediately adjacent the packing.

13. For a machine gun, the combination of a reciprocable barrel having its rear portion threaded and provided with an annular series of bevelled notches adjacent the threads, the said barrel having means thereon additional to the said notches and adapted to be engaged by a tool to prevent rotation and the said barrel also having an annular groove therein near the rear and spaced forward from the said notches and from the said means for preventing rotation, an annular packing carried by the barrel within the said groove, and a rotatable adjusting ring for the packing positioned within the said groove and having threaded engagement with the barrel. the said ring having its maximum diameter at least as small as the diameter of the barrel immediately adjacent the packing.

FREDERICK T. MOORE. 

